1. Field of the Invention
The invention relates to a display device comprising a display tube with a display screen, a deflection unit for deflecting at least one electron beam generated in the display tube, said deflection unit comprising at least a line deflection coil and a field deflection coil, and a field distortion correction circuit coupled to the deflection unit for correcting the field deflection.
2. Description of the Related Art
The invention also relates to a field distortion correction circuit.
A display device of the type described above is known from European Patent Application EP-A 201336 corresponding to U.S. Pat. No. 4,642,530. The display device described in this Patent Application comprises a field distortion correction circuit using a non-linear reactor, for example, a saturable transformer, in which a first modulation current, having a frequency which is a harmonic of the line frequency, is applied to an input winding of the reactor/transformer. This first modulation current is modulated by means of a signal at the field frequency. This makes it possible to correct pincushion distortion and/or gullwing distortion.
A drawback of this known display device including a field distortion correction circuit is that the reactor (saturable induction)/transformer used therein is expensive and that it is a large, complicated component having many branches, while the reactor does not have a satisfactory temperature stability. A further drawback of the reactor/transductor is that this element has a very detrimental influence on other elements of the display device.